To characterize the anatomical connectivity of the prelemniscal radiations (Raprl), a white matter region within the posterior subthalamic area (PSA) that is an effective neurosurgical target for treating motor symptoms of Parkinson's disease (PD). Diffusion-weighted images were acquired from twelve healthy subjects using a 3T scanner. Constrained spherical deconvolution, a method that allows the distinction of crossing fibers within a voxel, was used to compute track-density images with sufficient resolution to accurately delineate distinct PSA regions and probabilistic tractography of Raprl in both hemispheres. Raprl connectivity was reproducible across all subjects and showed fibers traversing through this region towards primary and supplementary motor cortices, the orbitofrontal cortex, ventrolateral thalamus, and the globus pallidus, cerebellum and dorsal brainstem. All brain regions reached by Raprl fibers are part of motor circuits involved in the pathophysiology of PD; while these fiber systems converge at the level of the PSA, they can be spatially segregated. Fibers of distinct and specific motor control networks are identified within Raprl. The description of this anatomical crossroad suggests that, in the future, tractography could allow deep brain stimulation or lesional therapies in white matter targets according to individual patient's symptoms.
Objective: Previous reports proposed prelemniscal radiations (Raprl) as a target to treat motor symptoms of Parkinson's disease, and this was found particularly effective to control rest and postural tremor. However, tremor of other etiologies has been seldom treated with deep brain stimulation or ablation in this target. We present a series of such cases successfully treated by Raprl radiofrequency (RF) lesions. Material and Methods: Six patients with predominant unilateral tremor on the right arm: 4 intention, 1 cerebellar and 1 rubral tremor, incapacitating in spite of at least 2 regimes of medical treatment at maximal tolerated doses, were operated under local anesthesia. RF lesions were performed in Raprl contralateral to most prominent symptoms. Patients had monthly evaluation of tremor severity through the Fahn-Tolosa-Marin Tremor Rating Scale and disability through the Tremor Disability Scale along a 1-year follow-up. Results: In 4/6 patients tremor was stopped by the simple insertion of an RF electrode in Raprl; in the other 2 cases, stimulation through the RF electrode at 100 Hz, with 100 µs and 1.0-1.5 V, stopped the tremor without side effects. Tremor disappeared in all cases immediately after surgery and partially reappeared in 2 cases with an amplitude about 20% of the preoperative condition. RF lesions in postoperative MRI ranked from 1.8 to 2.6 mm in diameter. Conclusions: RF lesioning in Raprl is a simple, highly effective, inexpensive way to treat tremor of different etiologies.
Objective:The authors aimed to analyze the current epidemiology of high- and low-grade gliomas, follow-up strategies, and prognosis in a national reference center of a developing country.Materials and Methods:Medical records of patients diagnosed with intracranial gliomas from January 2012 to January 2016 were reviewed. Data were classified by age, symptoms, Karnofsky functional scale (KFS), tumor location, extent of resection (EOR), histopathology, hospital stay, Glasgow outcome scale (GOS), adjuvant treatments, overall survival (OS), and mortality.Results:Astrocytomas accounted for 28.2% of the intracranial tumors and 53.5% were male. Headache was the most common symptom, while sensory disturbance was the least frequent. The right cerebral hemisphere was involved in 56.5% of cases and frontal lobe in 31.3%. Gross total resection (GTR) was achieved in 18.1% cases, 35.3% subtotal resection, and 46.4% biopsy. Regarding the astrocytomas, 43.3% were low grade and 56.4% high grade. Low-grade tumors had the highest frequency in the fourth decade of life, while Grade III and IV in the fifth and seventh decades of life, respectively. In high-grade lesions, there was a slight male predominance (~1.4:1). The initial KFS was regularly 80 for low-grade gliomas and 60 for high-grade. By 1-month postdischarge, the score decreased by 10 points. About half of the patients (47.5%) received adjuvant therapy after surgery. From the Glasgow Outcome Scale (GOS), the majority had a form of disability and 30-month OS was above 88% for Grade I-II and 0% for Grade III and IV.Conclusions:Astrocytic tumors were the most frequently noted intra-axial tumors. Age, histological grade, and EOR are important prognostic factors. These results are similar to other reports; however, increased variability was noted when treatment-related factors were considered. Additional studies are necessary to identify the factors related to these treatment results.Highlights: There are no data describing the basic epidemiology and prognosis of high-grade and low-grade gliomas in Mexico.Intracranial astrocytomas account for 28.2% tumors in our institution.Age, histological grade, and EOR are important prognostic factors.Poor overall survival was achieved in our target population.
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